Combating fire with ablative water

ABSTRACT

The application of ablative water in combating fire is improved by wetting the surfaces of the combustible materials to be protected with water containing a surfactant prior to the application of ablative water to such surfaces in order that the subsequently applied ablative water readily penetrates the combustible material down to where the fire is in order that the ablative water be available where it is required.

United States Patent 1151 3,647,001

Livingston 1 Mar. 7, 1972 54] COMBATING FIRE WITH ABLATIVE 3,229,769 1/1966 Bashaw et a1. ..l69/1 WATER 3,247,171 4/1966 Walker et a]. ..260/80.3

3,345,289 10/1967 Freifeldetal ....252/8.l 1 lnvemofi Willwm h-LivinaswmNorwwdMass- 3,354,084 11/1967 Katzer .252/2 [73] Assignee: Factory Mutual Research Corporation,

Boston-Providence Turnpike, Mass. Pfima'y Examinerjohn Goolkasian Assistant Examiner-D. J. Fritsch [22] Filed: Apr. 22, 1970 Attorney-Lane, Aitken, Dunner 81 Ziems [21] Appl. No.: 30,835 [57] ABSTRACT The application of ablative water in combating fire is im- [52] US. CL ..l69/l A, 169/ 1 B, 169/14, proved by wetting the Surfaces f h combustible materials to 252/21 252/8-05 be protected with water containing a surfactant prior to the [5 I] Int. Cl. ..A62 1/06, A62d l/UO p li ti of blative water to such surfaces in order that the [58] Field of Search "252/2, 3, 8.05, 315, 316; subsequently applied ablative water readily penetrates the 169/1 l l 14 combustible material down to where the tire is in order that the ablative water be available where it is required.

[56] References Cited 2 Claims, 1 Drawing Figure UNITED STATES PATENTS CONCv SOL'NDF GELLING AGENT SURFACTANT CARRIER WATER MAIN 12 14 11 15 FUSIBLE LINK 13 COMBATING FIRE WITH ABLATIVE WATER BACKGROUND OF THE INVENTION This invention is directed to the field of combating fires utilizing ablative fluid material systems.

An ablative material as comprehended within the present invention is a material which, when present in a layer of sufficient thickness, will permit thermal energy to be transmitted through its exposed outer surface but not completely through said layer, said thermal energy being absorbed within said layer so as to immediately transform the material of said layer into vapor without internal convection of said material, said vapor leaving said layer through its outer surface.

The use of an ablative fluid material to combat a fire in a building or other confined location by the application of, said material from an automatically operable fixed source such as an automatic sprinkler system is described in commonly assigned patent application of Livingston et al. Ser. No. 766,475 filed Oct. 10, 1968.

As described in the aforementioned Livingston et al. application water is converted to an ablative fluid material by the admixture therewith of a water-swellable cross-linked polymer. The formed ablative fluid material is in the form of a gel and is denoted ablative water.

Water-swellable cross-linked polymers useful as gelling agents to convert water to ablative water are described in Katzer U.S. Pat. No. 3,354,084 and Bashaw et al. U.S. Pat. No. 3,229,769. One useful water-swellable cross-linked polymer is sold by B. F. Goodrich Chemical Company under the designation Carbopol-960. Another useful water-swellable cross-linked polymer is sold by Dow Chemical under the designation of Gelgard M. Gelgard M is described in my copending application Ser. No. 13,179 filed Feb. 20, 1970 titled Slurry Additive for Ablative Water Fire Extinguishing Systems.

The ablative water system in addition to containing polymer gelling agent can also contain fire-extinguishing materials, such as alkali metal halides and diammonium phosphates and foaming surface active materials, as well as inorganic fire-retardant materials, such as diatomaceous earth, attapulgite and kaolinite. Generally speaking the choice of gelling agent and other fire retardant materials added will be dictated by con siderations having no relevance to this invention.

In addition the manner of preparing the ablative water system can introduce other materials into the system which are utilized for considerations having no relation to the fire combating characteristics of the system. Thus for example in automatic sprinkler systems it is desirable to premix certain solid water-swellable cross-linked polymeric materials used as gelling agents in the form of slurries using a liquid carrier. For example the polyacrylamide water-swellable cross-linked polymer gelling agents are usefully suspended in isopropyl alcohol or other suitable carrier and stored in slurry form for addition to water when it is desired to set up an ablative water system in fighting a fire. Furthermore the ablative water system can contain other agents desired to promote its effective delivery to the point of use. For example agents can be admixed in the ablative water system which reduce the friction in the pipe in which the system is delivered to its point of use, thus increasing the flowability of the ablative water system. Materials such as poly(ethylene oxides) are particularly useful for this purpose. Similarly the dispersion or emulsion of insoluble materials, and the rapid solution of soluble materials are enhanced by the addition of surfactants. Surfactants are sometimes found as components in ablative water systems for this purpose.

Thus, surfactants have been utilized in combination with ablative water, that is in admixture or solution therein, as foaming agents to provide fire-extinguishing effect or as dispersing or emulsifying agents for additives included in admixture with ablative water. Heretofore, it has not been known to utilize an aqueous surfactant solution applied separately from ablative water to increase the penetration of ablative water applied to combustible materials, both those which are burning and those which are to be protected, thereby reducing the overall ablative water requirements. This use of aqueous surfactant solutions is the subject of the present invention.

SUMMARY OF THE INVENTION In accordance with the present invention it has been found that the required amount of ablative water to combat a fire can be reduced and that more effective and rapid action in combating the fire can be obtained by first treating the fire, or more particularly, the combustible materials on fire and threatened by fire, with water containing a compatible surfactant, that is with a compatible aqueous surfactant solution which wets the surface of combustible materials which are threatened with fire and which are to be protected such that when the ablative water is subsequently applied the presence of surfactant on the surface of combustible materials aids in the rapid spreading of ablative water over the combustible materials and in the deep penetration of ablative water to where the fire is. The method of this invention is applicable with advantage to combating fire with ablative water whatever the mechanical technique of water application.

In accordance with this invention the pretreatment of combustible materials with water containing a surfactant should be of sufficient duration to wet the combustible materials, but should be terminated before substantial pooling and runoff of water occurs such that when followed by application of ablative water there is just sufficient wetting action to assist in penetrating the combustible materials which are threatened by fire and which are to be protected and the ablative water is not induced further to run off. The exact timing of the pretreatment will, of course, vary from fire to fire, although normally in an automatic sprinkler system it is desirable to apply the pretreatment water with surfactant utilizing the same sprinkler system as is subsequently utilized to apply the ablative water system. In such an arrangement, with water pressures the same, the pretreatment time is typically on the order of about 5 minutes, but can vary considerably from that time.

Generally any surfactant can be utilized in the pretreatment water system which is compatible with the gelling agent and other components of the ablative water system which follows in terms of application to the combustible materials. Those surfactants which are particularly contemplated are preferably wetting agents having the capability of reducing the surface tension of the water and desirably should be stable at temperatures at least up to the boiling point of water in order that they remain on the combustible surface to which applied while still wet.

Suitable surfactants are, for example, nonionic organic detergents. Ionic surfactants, such as anionic or cationic detergents, are not suitable since such surfactants are not compatible with the gelling agent component of the subsequently applied ablative water since on contact with ablative water they act to destroy the ablative nature of the ablative water.

Nonionic organic detergents suitable for use herein include, for example, polyethylene oxide condensates of alkylphenols where in the alkyl group contains from eight to 15 carbon atoms (e.g., t-octylphenol) and the ethylene oxide is present in a molar ratio of. ethylene oxide to alkylphenol in the range of 8:1 to 20:1; condensation products of ethylene oxide with the product resulting from the reaction of propylene oxide and ethylene diamine wherein the molecular weight of the condensation products ranges from 5,000 to 11,000; the condensation products of from about 5 to 30 moles of ethylene oxide with one mole of a straight or branched chain aliphatic alcohol containing from eight to 18 carbon atoms, e.g., condensation product of 6 moles of ethylene oxide with one mole of lauryl alcohol; higher alkyl di-lower alkyl amine or phosphine oxides, e.g., dodecyldimethylamine oxide or dodecyldimethyl phosphine oxide; alkyl methyl sulfoxides such as dodecyl methyl sulfoxide.

ll,647.00l

Preferred nonionic detergents for use herein are the polyoxyethylenated alkylphenols described above.

BRIEF DESCRIPTION OF THE DRAWING For a more complete understanding of the practical application of this invention, reference is made to the appended drawing which illustrates a flowsheet of an automatic sprinkler system utilized in carrying out this invention,

DETAILED DESCRIPTION OF THE INVENTION In the drawing the reference numeral generally designates a sprinkler system including line 11 connected at one end of a water main l2 and leading to outlet nozzles 13 lonly one is shown). Nozzles 13 can be any nozzles typically used in automatic sprinkler systems and are usually provided with a fusible link in a conventional manner, such that upon the temperature at the location of the nozzle reaching a predetermined maximum, the fusible link abruptly melts, opening a connection between the nozzles 13 and line 11 to permit water to flow from main 12 through nozzles 13 in a suitable spray pattern determined by the location of nozzles Line 11 adjacent main 12 is connected through lateral connections l4 and 15, respectively, to holding tanks 16 and 17. Each line 14 and 15 is provided with a normally closed, solenoid-operated valve, indicated by the reference numerals l8 and 19, respectively, which when actuated is operable to make connection between its respective holding tank 16 or 17 and line 11 through its associated line 14 or 15. In addition each of lines 14 and 15 contains a suitable metering device, such as an orifice plate, such that flow through the line from its associated holding tank 16 or 17 is at a regulated rate when valve 18 or 19 is opened.

A flow sensor device 20 is connected in line 11 and is operalble in response to flow through line 11, as occurs when nozzles 13 open, immediately to actuate valve 18 such that liquid contained in holding tank 16 is bled into the flowing stream in line ll. Sensor 20 also upon actuation in response to flow in line Ill immediately operates to actuate a time delay device 21 which in turn operates after a predetermined time delay to actuate valve 19 opening communication through line 15 between holding tank l7 and line 11 such that liquid in holding tank 17 is then metered into line 11. Time delay device 21 also responds on timing out to disconnect the operative circuit between sensor 20 and valve 18 to cause a valve 18 to close simultaneously with the opening of valve 19, thus discontinuing the flow of material from tank 16 into line 11 at the same time flow from tank 17 starts into line 11.

In operation holding tank 16 contains a premixed concentrated solution of water and surfactant. For example the surfactant can be Triton N-lOl, a proprietary product manufactured by Rohm & Haas Cov which is a polyethylene oxide condensate of nonyl phenol having about [2 to 13 moles ethylene oxide per mole of phenol. In such case the Triton N-lOl is mixed in tank 16 with water on the basis, for example, of five parts by weight of Triton N-lOl with 100 parts by weight of water, and line 14 is adapted to meter liquid from tank 16 at the rate of one volume per 100 volumes of water in line 11.

In a typical installation the gelling agent can be a commercially available polyacrylamide sold under the trade name Gelgard" referred to hereinbefore, In preparing the premix of the gelling agent for storage in holding tank 17 the Gelgard which is a solid particulate material is slurried at the rate of i140 pounds per barrel of isopropyl alcohol tone barrel isopropyl alcohol equals 354 pounds net). Added to this mixture in holding tank 17 are 1,000 mlv Polyox FRA" *{Polyox lFRA is a high molecular weight poly(ethyleneoxide) sold by Union Carbide Corporation.) per barrel of isopropyl alcohol to reduce the friction of flow in pipe 11 and through nozzles l3 when the mixture in holding tank 17 is introduced to pipe 11. In accordance with William L. Livingston copending application filed concurrently herewith titled "Preparation of \blative Water" there is also added to the material in holdin tank 17, 20 pounds per barrel of isopropyl alcohol of Cab-o-sfi M-S, a proprietary product which is a colloidal pyrogenic silica having a surface area of 200 square meters per gram and sold by Cabot Corporation and which in accordance with the above copending application functions to stabilize the slurry in holding tank 17 to permit its storage without agitation for substantial periods of time, i.e., 6 months to a year. The metering rate of liquid through line 15 should be adjusted to mix the slurry in tank 17 with water in line 11 to set up a gel. Normally the thickening agent, Gelgard, illustrated sets best at l3 pounds per gallons of water.

In accordance with the invention when a fire occurs at the location of any of nozzles 13 causing their fusible links to abruptly melt and permitting flow through them, the consequent flow of water in pipe 11 actuates sensor 20 immediately actuating valve 18 such that the concentrated surfactant solution in holding tank 15 is bled into line 11 to produce a concentration of the surfactant on the order of 0.05 weight percent. Time delay device 21 is preset in accordance with the design considerations of the particular sprinkler system 10 and typically is preset to time out after 5 minutes. The preset timing of time delay device 21 should be set such that the water-containing surfactant being delivered through nozzles 13 to the fire is sufficient to cause penetration of the tire by the surfactant solution deep into the fire without excess to the extent that water pools or runs off. The action of the fire causes the water to boil off at the hottest points, but leaves those combustible surfaces not yet burning or overheated relatively wet such that when time delay device 21 times out to introduce the gelling agent from holding tank 17 to line 11 and to discontinue the flow of surfactant from holding tank 15, the ablative water system formed by the addition of gelling agent to the water in line 11 which is then delivered to the fire slides rapidly over the combustible materials which remain wet to the point where the fire has dried, thus piling up ablative water at the location of the tire itself where its action is most effecme.

Where better coverage of ablative water is required with respect to a water-repellent surface, such as the surface of a stack of rubber tires, it can be desirable to apply separate streams of aqueous compatible surfactant solution and ablative water to said surface at the same time whereby more of said surface is provided with a thicker layer of ablative water. Such coextensive application can be carried out utilizing two automatic sprinkler systems, one to apply ablative water and the other to apply aqueous surfactant solution.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed is:

l. A method of combating fire upon an indication of the occurrence of fire among combustible materials which comprises, applying to said materials an aqueous nonionic organic surfactant solution which is compatible with ablative water so as to wet the surface of said materials and thereafter applying to said combustible materials an ablative water system whereby the penetration and coverage of said ablative water is increased.

2. A method as described in claim 1 wherein said surfactant is a polyethylene oxide condensate of alkylphenol wherein the alkyl group contains from eight to 15 carbon atoms and the ethylene oxide is present in a molar ratio of ethylene oxide to alkylphenol in the range of 8:1 to 20:]. 

2. A method as described in claim 1 wherein said surfactant is a polyethylene oxide condensate of alkylphenol wherein the alkyl group contains from eight to 15 carbon atoms and the ethylene oxide is present in a molar ratio of ethylene oxide to alkylphenol in the range of 8:1 to 20:1. 